In general, the present invention relates to the field of communication systems, more particularly, to a communication device that operates within a plurality of wireless communication networks.
Communication devices that provide for communication of voice and data are extensively used in telephony and wireless communication systems. For example, European Telecommunication Standard Institute (ETSI) has specified a Global Standard for Mobile Communication (GSM) that uses time division multiple access (TDMA) to communicate control, voice and data information over radio frequency (RF) channels. In the U.S., Telecommunication Industry Association (TIA) has published a number of Interim Standards, such as IS-136, that define various versions of digital advanced mobile phone service (D-AMPS), and analog advanced mobile phone service (A-AMPS), with the capability of transmitting voice and data to subscribers. These types of communication systems cover a geographical area that is subdivided into communication cells, which together provide communication coverage to a service area, for example, an entire city.
Often, communication service subscribers utilize the communication devices for services that are provided over multiple-networks operated by various service providers. For example, subscribers carrying dual-mode wireless communication devices can place calls in a digital system, such as D-AMPS system, as well as an analog system, such as A-AMPS. Depending on the type of available service, i.e., digital or analog, at a local or roaming service area, the dual-mode communication device can automatically provide calling capabilities by detecting the configuration of the available service in the service area. Based on the detected configuration, the communication device then enters a suitable operating mode, i.e. digital or analog mode, thereby allowing the subscriber to place calls in one of multiple networks. Multiple networks may also serve subscribers making domestic or international calls. For example, a subscriber may make calls from a domestic service area that is served by a local IS-136 service provider to an international service area served by one or more GSM networks and vice versa.
When using a communication device within multiple networks (i.e., digital/analog, local/roaming, or domestic/international), calling codes may have to be dialed at the communication device to route a call to a particular service area. Calling codes can be, for example, a country code and an area code that are prefixed to a local call number belonging to a service area to which the call is directed. When a call is placed using a communication device that is subscribed to a local service area, then the subscriber only needs to dial a local call number, without the need to dial additional calling codes for completing the call. However, when the subscriber travels to a different service area, for example, a service area that requires a dual-mode communication device to switch from a digital mode to an analog mode, the subscriber may be required to dial calling codes in addition to the local call number to complete the call. As such, the subscriber may be encumbered by complicated requirements for dialing calling codes when traveling from one service area to another service area.
Moreover, in GSM systems, each GSM communication device includes a slot for inserting a Subscriber Identification Module (SIM) card that stores relevant data to identify the device to a service provider network for security and billing purposes. As such, the same GSM communication device may assume different identities depending on the data that is stored in an inserted SIM card. The ability to insert different SIM cards into the communication device further complicates the calling code dialing requirement for placing a call. For example, if a subscriber uses a SIM card associated with a service provider in the United States, the subscriber must only dial the local call number to complete a local call. However, if the subscriber travels to Germany with the same SIN card and places a local call within the network of a German service provider, the subscriber would need to dial several calling codes before dialing the local German call number. On the other hand, if the subscriber in Germany inserts a SIM card associated with the German service provider, the subscriber could simply dial the German local call number without having to dial any calling codes to complete the call in Germany. However, for dialing a number within the U.S. service area, the subscriber would need to dial additional calling codes for completing the call.
As can be appreciated from the foregoing, the subscribers of communication services are subject to complex calling code dialing requirements when making calls in multiple networks. Accordingly, there exists a need to simplify the requirement for dialing of calling codes at a communication device that operates in a plurality of wireless communication networks.